Closest to the invention (the prototype of the invention) is a classic method of gas exchange of four-stroke internal combustion engine. This method comprises opening of the intake valve on the intake stroke and opening of the exhaust valve on the power stroke and exhaust stroke and is implemented in most PICE with the induction system and the exhaust system, including the PICE with the induction system having a device for air charging, in other words—device (or devices) for air compression, for example, compressor of turbocharger, and with the exhaust system having the device (or devices) of the combustion products expansion, for example, turbine of the turbocharger.
A well-known negative attribute of the classical method of gas distribution is relatively small flow area of intake and exhaust valves. Small flow area of the valves limits the quality and speed of gas exchange, therefore, reduces the performance of the engine and limits engine uprating. Method of gas distribution through sleeve valve [Ricardo, Sir Harry R.; Hempson, J G G (1968). The High-Speed Internal-Combustion Engine (Fifth ed.). London and Glasgow: Blackie & Son. pp. 290-322.] is used ports in the cylinder sleeve. Mentioned ports in the sleeve have a bigger flow area than the valves. But method of gas distribution through sleeve valve (which is a method-analog) is complicated, so was uncompetitive compared to the method of gas distribution through the valves. Disadvantage of the prototype, as well as of the method-analog, is the small scavenging. Small scavenging not cool details of exhaust system and they (correspondingly, the exhaust valve and moving sleeve) have big heat stress.
Insufficient scavenging leads to the high thermal stress and high temperature not only of details of exhaust system, but of the cylinder head, piston and other engine details, as well as leads to an incomplete cleaning of the cylinder from the combustion products.
In the method—analog there are the heat and mechanical stresses in the sleeve ports, more precisely, in the edges of the ports and ports-related mechanisms. This stress associated with the fact that the ports: a) are located at the top of the cylinder, where the gas has a high temperature and pressure, and b) open only at the end of the gas expansion and exhaust, and through the ports the hot products of combustion outflows; scavenging is very small or absent.
On the high frequency rotation and/or high loads, when there is excess pressure ratio in the compressor of turbocharger, insufficient scavenging leads to too much value of the maximum combustion pressure.
Besides, methods of gas distribution: the method-prototype and the method-analog do not allow supply a portion of an engine's hot exhaust gas back to the engine cylinder at the last stage of the intake stroke. Said hot exhaust gas back to the cylinder is useful at start-up, idling and low loads.
Relatively cold air (cold fresh charge) at the last stage of the intake stroke and first stage of the compression stroke reduce starting characteristics, a little reduce efficiency and ecological characteristics at starting, idling and low loads when the method-prototype and the method-analog is used.